Injectors with a needle are used to deliver medication directly to animals. As one example, injectors are used to deliver medication directly to the rumen of an animal.
Disclosed in U.S. Pat. No. 4,530,695 is an injector having a needle enabling a medication to be directly delivered via the needle. The injector has an interacting piston and cylinder. The injector is "cocked" by a user tensioning a spring. The forward portion of the injector is provided with a trigger mechanism which when activated releases the cylinder which moves over the piston to cause the medication to be injected via the needle. The user then recocks the device. The trigger is operated by the forward portion of the injector contacting the skin of the animal. This injector in its preferred construction was adapted as an intraruminal injection apparatus. Another intraruminal injector is disclosed in U.S. Pat. No. 4,403,989. In this device, an interacting piston and cylinder are moved by the operator to cause injection to take place. A trigger mechanism releases the piston and cylinder for this relative movement. Again it is the the operator which provides the force required to operate the device. A multi dose injector is described in U.S. Pat. No. 2,821,193. In this device, a pump mechanism is employed to operate the device. The pump mechanism is trigger operated requiring the operator to reciprocate the trigger to operate the pump mechanism. Again it is the operator which provides the force to operate the device. A further multi-dose injector is described in U.S. Pat. No. 3,400,716. This device requires the operator to push the device against the skin in order to operate the piston and cylinder assembly. Again the user requires the force to operate the device.
Disclosed in U.S. Pat. No. 4,676,781 is a still further ruminal injector. This device has an interacting piston and cylinder but no trigger mechanism. The device is operated by the user pushing the device against the animal. Again the user provides the force required to operate the device. European Patent Publication 0080112 also discloses an injector. The injector is provided with a reservoir with a trigger mechanism which pumps the vaccine from the reservoir to the needle. Again the operator provides the force required to operate the device.
A still further injector is described in German Patent Specification 1,491,840. This device uses an interacting piston and cylinder and a spring mechanism which is cocked prior to use. Again the user provides the force required to operate the device.
In each of the above described devices, it is the user that provides the force required to operate the device.